Performance Evaluation of a Pebble Bed Solar Crop Dryer
The design, development and test performance evaluation of an integrated of passive solar energy crop drying system was undertaken. The solar crop dryer consists of an imbedded pebble bed solar heat storage unit/solar collector and crop drying chamber measuring 67 cm x 110 cm x 21cm and 50 cm x 90 cm respectively. The crop-drying chamber is made of drying trays of wire gauze while the roof is made of transparent glazing. Test performance evaluation of the solar crop dryer indicates that maximum absorber temperature of 72 0C, heat storage bed temperature of 58 0C and chamber temperature of 57 0C were obtained using the dryer when the maximum ambient temperature was 34 0C. Further test using cassava, showed a moisture reduction from 73% initial moisture content to 10.2% final moisture content in 3 days of drying process while open air sun drying was 22.2% under the same period of drying.
Products dried under the passive solar crop dryer were of high quality while there were mould build up on the open air sun dried products. This indicates that drying under solar crop dryer offers high quality products and is time saving than the open-air sun drying.